Field of the Invention
This invention relates to the coupling of light into and out of an optical fiber and, more particularly, to the coupling of light into and out of an optical fiber from the side thereof without the use of separate lenses and mirrors.
Optical fibers are now relatively well known light transmission mediums. The most common mode of coupling light into and out of the optical fiber is to butt the end of the fiber to the optical source so that the light is directed straight into the end of the optical fiber. There are many situations where the optical fibers cannot be directly butted to the light source or detector. For example, where the light source is a top surface light emitting diode located in a high density environment such as is found on a card in a package of closesly spaced parallel cards as is found extensively in present day electronic packaging. One solution is to bring in the optical fiber parallel to the card and provide a 90.degree. bend so that the end of the fiber can be butted to the light source or detector. It has been found that the 90.degree. bend creates losses in the optical fiber, particularly in low loss optical fibers, and should be avoided if possible. Another solution to the problem has been to side-couple the light into and out of the optical fiber by the use of a mirror attached near the end of the fiber. A lens can be used between the mirror and the light source to collimate the light and thus provide the coupling of the light into the optical fiber. It will be appreciated that the use of lenses and mirrors in the high density situations afforded by large scale integrated circuitry is just not practical.